<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <title>作业</title>
</head>

<style>

    *{
        margin: 0px;
        padding: 0px;
        outline: none;
        font-size: 14px;
    }

    html,body{
        height: 100%;
    }

    .box{
        /*box-sizing: border-box;*/
        padding: 20px;
        height: calc(100% - 40px);
        background-color: pink;
    }

    .left_content{
        width: 200px;
        height: 100%;
        float: left;
        background-color: #b986c7;
    }

    .right_content{
        padding: 20px;
        background-color: #3c81af;
        min-height: calc(100% - 40px);
        margin-left: 220px;//浮动到最左边了
    }

</style>

<body>

<div class="box">

    <div class="left_content"></div>

    <div class="right_content">



    </div>

</div>

</body>
</html>